Talk:Audio compression (data)
From Wikipedia, the free encyclopedia
 |
This article is within the scope of the Professional sound production WikiProject, a collaborative effort to improve Wikipedia's coverage of the technology, equipment, companies and professions related to professional sound production. If you would like to participate, you can visit the project page, where you can join the project and see a list of open tasks. |
| Start | This article has been rated as Start-Class on the assessment scale. |
There's an interesting aside here relating to midi and pianola. Both these techniques are extremely effective lossless compression technologies but solve the problem in a quite different way. User:Rjstott
I have moved the page Audio compression to Audio data compression because I believe it more accurately describes the topic of discussion and leaves the original page for a discussion of audio compression in recording.
-- Jul 7, 2003 Ap
- Audio compression is now a disambig, as it should be. - Omegatron 23:02, Apr 6, 2005 (UTC)
Under the section titled "Lossless compression", it is said "...audio waveforms, which are generally difficult to simplify without a (necessarily lossy) conversion to frequency information...". I dispute that conversion to frequency-domain is necessarily lossy. 57.66.65.38 13:06, 15 January 2007 (UTC)Andrew Steer www.techmind.org
can someone tell me any simple algorithm to compress a wav file back to a wav file. i'm not sure if lzw will work. Xhamlliku
[edit] Latency
"In general, latency must be 15 ms or lower for transparent interactivity."
This is nonsense. Transaltanic telephones calls always have a latency significantly greater than this, thanks to the distances involved:
15,000,000 round trip / 300,000,000 metres per sec = 50 ms.
With modern telephone systems it is difficult to impossible to notice any latency. I have chopped out the above sentence.
And I think that the sentence should be added back. Wieslaw W's work at McGill shows that very short latency is utterly essential for good "tightness" of a band. A conversation is a completely different ballgame, and even then, latency is shown to cause user confusion. Btw, telephones do not propagate at anything close to the speed of light, the cables are about 1/2c, and there is lots of buffering, etc, in the middle that adds even more latency. Then there's synchronous satellite delays for satellite carried calls... Woodinville (talk) 22:36, 4 February 2008 (UTC)
[edit] lzw compression of wav file
I don't know where user Xhamlliku went but I know of no reason lzw compression wouldn't work with a .wav file.. Charlie 11:52, 26 October 2005 (UTC)
Actually, ZLW won't work with a .wav file unless you compress truly enormous volumes of data. LZW regards the sequence 8 4 2 1 as a different sequence than 24 12 6 3. Any kind of linear predictor regard them as a single initial value with the same predictor coefficients. ZLW doesn't consider that kind of source model in the short term, and any of LPC or high-resolution frequency analysis will do very well with such a sequence. Since nearly all audio consists of autoregressive sequences like this, this shows why ZLW won't work so well on reasonable-sized files. Woodinville (talk) 22:34, 4 February 2008 (UTC)
[edit] Compression ratios are similar to what?
"The primary users of lossless compression have been audio engineers, audiophiles and those consumers who want to preserve an exact copy of their audio files, in contrast to the irreversible changes from lossy compression techniques such as Vorbis and MP3. Compression ratios are similar to those for lossless data compression (around 50-60% of original size)."
I'm wondering if the second sentence could perhaps be more precisely worded? If the compression ratios are similar for lossy and lossless compression, that would seem to remove the primary incentive to go with lossy compression, which is to save space. My observation is that there is a fairly significant difference in storage space requirements between WM9 lossless compression and the highest quality WMA lossy settings when ripping CDs, which implies the compression ratios aren't all that similar. JohnMajerus 05:51, 6 November 2007 (UTC)
